In a sleepy lagoon off the coast of Japan, behind a wall of barbed wire and “Keep Out” signs, lies a shocking secret. It is here, under cover of night, that the fishermen of Taiji engage in an unseen hunt for thousands of dolphins. The nature of the work is so horrifying, a few desperate men will stop at nothing to keep it hidden from the world. But when an elite team of activists, filmmakers and free divers embark on a covert mission to penetrate the cove, they discover that the shocking atrocities they find there are just the tip of the iceberg.